Vodafone Group is likely to file a draft prospectus for the planned IPO of its Indian business in August with the listing expected in the fourth quarter, in a deal seen raising as much as $2.5 billion, people with direct knowledge of the matter told Reuters.

The British telecoms group, India`s largest mobile operator after Bharti Airtel , has begun work on the prospectus that would incorporate the Indian unit`s financials for the first half of the calendar year, they said.

Vodafone hired Bank of America Corp , India`s Kotak Investment Banking, UBS AG in April as global coordinators for the IPO, set to be India`s biggest stock market listing since 2010.

A London-based Vodafone spokesman declined to comment on the timeline, saying the potential India IPO was a "lengthy process" and no decision would be made until the company was at the end of it. Sources declined to be identified as the information is not public.